Generally, conventional exercise bicycles are operated by pedalling an adjustable resistance wheel so as to exercise the leg and feet muscles. In such conventional exercise bicycles, the pedalling resistance is adjusted manually. However, conventional exercise bicycles provide only an indoor exercise. The user can only pedal mechanically without feeling any road condition variation and acquiring any experience in handling such road conditions. In other words, exercising on a conventional exercise bike lacks interest, and may limit the user's will due to monotonous motion, thus preventing development of the user's physical strength. As a result, the exercise results may be lower than expected.